Everyday you meet new different people. Make it to the point that at the end of the day you can make at least one person happy just by letting them see you smile. Even the person you see in the mirror.
When I was little girl my mom always told me that happiness was the key to life. When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment and I told them they didn't understand life.
Find someone who isn't afraid to to admit that they miss you. Someone who knows that you're not perfect, but treats you as if you are. Someone whose biggest fear is losing you, one who gives their heart completely. Someone who says I love you and means it. Last but not least, find someone you wouldn't mind waking up with you in the morning, seeing your wrinkles and your gray hair but still falls in love with you all over again.